#include<bits/stdc++.h>
using namespace std;
int a[105];
int main(){
    int n,suml=0,sumr=0,summid;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
	    cin>>a[i];
	}
	int l,r;
	cin>>l>>r;
	for(int i=1;i<=n;i++)
	{
		if(a[i]>r)sumr+=a[i]-r;
		if(a[i]<l)suml+=l-a[i];
		if(a[i]>=l&&a[i]<=r)summid+=r-a[i];
	}
	if(suml>=sumr&&summid>=(suml-sumr))
	{
		cout<<suml;
		return 0;
	}
	else if(suml<=sumr&&summid>=(sumr-suml))
	{
		cout<<sumr;
		return 0;
	}
	else cout<<-1;
    return 0;
}